1. Field of the Invention
The present invention relates to a sensor device and more particularly to a multi-optical axis photoelectric sensor.
2. Description of the Background Art
A general multi-optical axis photoelectric sensor comprises a light emitting part in which a plurality of light emitting elements are arranged in a row, and a light receiving part in which the light receiving elements as many as the light emitting elements are arranged in a row. The light emitting elements and the light receiving elements are arranged so as to be opposed to each other. The light emitting part and the light receiving part are connected through a communication line in general. On the side of the light emitting part, each light emitting element sequentially emits light, and on the side of the light receiving part, each light receiving element corresponding to each light emitting element receives the light and outputs the amount of received light at the timing synchronizing with the light emitting operation of the light emitting element. Thus, the light shielding state with respect to each optical axis of the multi-optical axis photoelectric sensor is sequentially detected. In the light receiving part, it is determined whether an object exists in a detection area with the detected result with respect to each optical axis or not and a signal showing the determined result is outputted.
Depending on the setting state of the multi-optical axis photoelectric sensor, even when the light emitting part is set in a state in which the light is not emitted, the light receiving part receives ambient light in some cases. The ambient light causes the malfunction of the sensor. For example, the multi-optical axis photoelectric sensors are closely set in a manufacturing field in many cases. Light from one sensor becomes the ambient light for another sensor.
Thus, measures against the ambient light is most important in setting or adjusting the multi-optical axis photoelectric sensor. In this respect, the user has to grasp the incident ambient light. For example, a photoelectric sensor disclosed in Japanese Unexamined Patent Publication No. 11-260215 (patent document 1) comprises a display device displaying the detection of the ambient light. Thus, the operator who sets the photoelectric sensor can easily find that the ambient light is inputted to the photoelectric sensor.
However, according to the photoelectric sensor disclosed in the Japanese Unexamined Patent Publication No. 11-260215 (patent document 1), the operator cannot find which optical axis has the incident ambient light among the plurality of optical axes. Therefore, in a case where there are many optical axes because a sensor head is long, or in a case where there are many sensors, it takes much time for the operator to specify the generation source of the ambient light.